Bradykinin (BK) reportedly increses the uptake of glucose and branched aminoacids in vivo. Preliminary data from our laboratoary using isolated rat adipocytes indicate that the effect on glucose uptake is mediated through a potentiation of insulin action. Because the vasoactive properties of BK and kallikrein (KL) result in augmented local blood perfusion and substrate flow, insulin potentiation may simultneously increase the rate of substrate uptake and metabolism, thereby bridging substrate availability and utilization in insulin target organs. In order to study the physiological relevance of these BK, and KL and the carbohydrate metabolism of isolated rat adipocytes both basally and with insulin stimutation. Transport of 2-deoxyglucose and glucose oxidation to C02 will be studied. The mechanism of these BK and KL effects will be investigated at a prereceptor, receptor, and postreceptor level with respect to insulin action. For this, BK and KL potential effects on isolated rat adipocytes and plasma membranes thereof will be examined with regard to: a) insulin degradation; b) insulin receptor affinity and number; c) kinetic properties and energy of activation of basal and insulin-stimulated hexose transport; d) formation of the insulin chemical mediator or secondary messenger; and e) role of protaglandins. FUrther studies will be directed to the characterization of putative BLK receptors in purified rat adipocyte plasma membranes, and we are proposing to determine the kinetics and pH optimum of BK binding, affinity, and number of BK receptors and potential interaction between BK and insulin binding sites. The physiological relevance of putative adipocyte BK receptors will be investigated by correlating the effects of various BK analogs on insulin-stimulated adipocyte hexose transport with their binding to adipocyte plasma membranes. These studies will add a new dimension to established hemodynamic actions of BK and KL, and suggest a role for the KL/BK system in the regulation of metabolic subtrate flow and utilization.